The association between levels of alcohol and tobacco use is well documented. Heavy drinkers and alcohol dependent subjects are more likely to smoke and smoke more frequently than light to moderate drinkers. Indeed a number of studies have suggested that nicotine dependence is an extremely common co-morbid condition for alcoholics in treatment. With mounting evidence of the deleterious health effects of heavy concurrent use of these substances, there has been increasing interest in devising treatment and prevention strategies that may simultaneously target alcohol and tobacco. Cross addition treatment and prevention is limited, however, by the fact that little is known about the mechanisms underlying the combined use of these substances. The present proposal addresses hypotheses derived from information processing models of substance use regarding the reciprocal influences of substance related cues. According to this view, with repeated co- occurrent use of two substances, cues for one substance may serve to activate memory representations underlying the use of the other thereby making associated substance use more likely and/or more intense. Using a sample of nicotine dependent heavy social drinkers, the current proposal investigates the hypothesis that smoking cues may activate or prime memory structures that mediate alcohol use. Through modifications of the Stroop color naming task, two experimental studies are proposed to investigate: (1) the influence of smoking cues on cognitive processing of alcohol- related information, (2) the effects of prior and concurrent smoking cues on drinking behavior, and (3) the association between cognitive processing measures of alcohol-tobacco interactions and drinking behavior in the presence of smoking cues. The results of this project will provide a clearer understanding of how the continued use of tobacco may influence attempts to control alcohol use. Moreover, it will provide the basis for a research program which seeks to develop integrative cognitive assessment and treatment approaches for concurrent alcohol and nicotine dependence.